A: from the difference of raw materials

Stainless steel elbow: 304 l, 316 l, ASTM/ASMEA403WP304-304 - l - 304 - h - 304 ln - 304 n, 310 s, SUS304, 30408, etc.

Carbon steel elbow: ASTM/ASMEA234WPB, WPC, 20 #, Q235B, Q245R, A105, etc.

Alloy steel elbow: 16 mn, Q345B, Q345R, ASTM/ASMEA234, WP1 - WP12 - WP11 - WP22 - WP5 - WP91 - WP911, 12 cr1mov, 15 crmov, 35 crmov, etc.

Two: the difference from the specification

Gb, two standard, non-standard, electricity standard, vessel standard, standard, water standard, American standard, Germany standard, Japanese standard, the standard and so on.

National standard specification is common: GB/T12459-2017, 2 standard and non standard is in the national standard on the basis of wall thickness, length, the degree of reduction data. General quality contrast is: national standard or two standard or nonstandard.

Three: from the production process

Elbow push system (applicable to bend with thin wall thickness system, also called the stamping elbow).

Suppress elbow (suitable for wall thickness of the thicker elbow, also called thermal bend).

Forging bend: (socket pipe pieces compared commonly use this technology, and perhaps the supercritical pressure elbow) stamping elbow its smoothness is better, and welding bending it is not very coordinately, winding radius of both types of small, generally is about 1 times the diameter of the pipe, and common bending radius of the twists and turns of about 8 times of the pipe diameter, its smoothness and also blunt bending.

Four: the difference from the welding process

Butt welding elbow: (is two pieces of steel plate through the press processing into two slices bend after the film, made by splicing welding type, suitable for outer diameter diameter greater than 700-2000 - mm).

The mitre elbow (it can be on the pipe or plate).

Five: to difference from weld process

Seamless elbow (it is seamless tube directly by hot-pressing pushed into one seamless elbow).

Straight seam pipe bend (is with straight seam welded pipe system of stamping elbow, is called a joint elbow).

Six: from the Angle of winding radius R

According to the curvature of the bend radius to points: can be divided into long radius elbow and short radius elbow. Long radius elbow refers to its radius of curvature is equal to 1.5 times the outer diameter of tube, R = 1.5 D. Short radius elbow refers to its radius of curvature is equal to the pipe diameter, R = 1.0 D. To bend diameter (D, R for the radius of curvature). Elbow and times, usually we call big times elbow bend pipe may be greater curvature, is winding radius R 2 d or higher, is greater than 2 times the radius of elbow, * * * can reach 30 times larger, 50 times, such as radius of large multiples of twists and turns, some across the bridge of the bend is such, across the radius